Age-related histological changes in rat mandibular condyle

Abstract

: The effect of aging on rat mandibular condyle was histologically assessed using 1-, 4-, 9-, and 16-month-old male Fischer rats (Eight rats of each group) . The medial and anterior portions of the condyle protruded with age . The hypertrophic cell layer of the condylar cartilage occurring up to 4 months was no longer observable at 9 months, after which calcification of the cartilage layer with a tidemark was featured . The chondrocytes in the calcified cartilage layer were reduced in size and intensely stained by toluidine blue . A mineralizing front was formed parallel to, and migrated toward, the condyle surface . At 9 months, osteon-like osteogenesis occurred around blood vessels on the border between the calcified cartilage and the subchondral bone . Condyles of 16-month-old rats exhibited osteosclerotic changes. The calcified cartilage of the middle portion of the condyle formed a remarkably thick layer . The increased volume of the trabecular bone appears to lead to enhanced osteosclerotic changes of the condyle . The aging-related protrusion of the anterior and medial portions of the condyle could be the result of a combination of mechanical forces, e .g ., occlusion and mastication . Further, our study revealed that the turnover from cartilage to bone occurring in rat condyle through the process of aging involved an osteon-like bone formation around the blood vessels on the border between the calcified cartilage layer and the bone . This process differs from the endochondral ossification process observed in younger rats .

Changes in type I, II, and X collagen immunoreactivity of the mandibular condylar cartilage in a naturally aging rat model

“…This study confirmed that the hypertrophic cell layer of the mandibular condyle disappears in the course of aging, implying changes in the cartilage calcification and ossification processes [1,[19][20][21].…”

“…Of these changes, calcification of the mandibular condylar cartilage can be considered a key element for clarifying the relationship between aging and concomitant changes occurring in the mandibular bone. We have previously reported that in the course of aging the hypertrophic cell layer gradually decays while endochondral ossification ceases to occur and the calcified cartilage layer gains in thickness [1]. Previous reports [1][2][3][4] led us to consider that the morphofunctional characteristics of the condylar cartilage change with age.…”

“…We have previously reported that in the course of aging the hypertrophic cell layer gradually decays while endochondral ossification ceases to occur and the calcified cartilage layer gains in thickness [1]. Previous reports [1][2][3][4] led us to consider that the morphofunctional characteristics of the condylar cartilage change with age. Similarly, cartilage matrix proteins synthesized by chondrocyte in the mandibular condyle may change in the course of aging.…”

Alteration of BMP‐4 and Runx2 expression patterns in mouse temporomandibular joint after ovariectomy

“…The steady BMP‐4 expression seen in the control group is consistent with the findings of Koike et al (1995). They found that the bone mass increase of the subchondral and central regions in a sham group corresponds with the age‐related increase (Koike et al , 1995). In the OVX group, BMP‐4 was highly expressed throughout the TMJ.…”

TMJ Degenerative Changes in SAMP3 Mice by Occlusal Disharmony and Aging

“…These findings closely align with another report that OA is associated with accelerating endochondral ossification 30) . Wnt/ -catenin plays an important role in the articular chondrocyte function, as well as in cartilage development at the pre-hypertrophic zone 31,32) . Therefore, we examined -catenin expression in both control and experimental groups.…”